Saturday, August 2, 2014

Federal Boston Desk Conservation Report

Before Treatment

Object Description:  Federal  desk attributed to Boston with mahogany doors and tiger maple veneer drawer faces and desk top lid.

Dimensions:  (h) 51 ½” (w) 41 3/8” (d) 21 ¼”

Before Treatment


Object Condition: The surface was severely damaged from a water leak. The coating had lost optical saturation and was severely blanched in many areas. There were numerous areas of veneer crossbanding lifting or completely missing. A section of the proper left corner molding was detached and another was completely missing. Additionally, the writing surface was at some point removed and the substrate had been varnished. 

Before Treatment

Before Treatment

Before Treatment

Inscriptions

Before Treatment

Before Treatment


Object Treatment: 

The portions of the veneer that were lifting were readhered with animal hide glue. Missing portions of crossbanding received new veneer patches from old stock. This veneer stock was selected for visual continuity with the patina of the entire desk.

Crossbanding detached


Readhering crossbanding

Top before ethanol treatment

The blanching in the coating was removed with a gelled ethanol resting on isolating layers of towel. This solvent microclimate was very effective after only a few minutes. The moisture was released with no noticeable softening of the varnish. All blanched areas treated were successful with the exception of the desk top lid due to considerable loss of coating.

Gelled ethanol isolated from surface. Solvent vapor at work!

Treatment success

Continued...

Ethanol vapor success!


B-72 brushed into degraded varnish

Once the varnish treatments were complete, optical saturation was restored by brushing one application of a 10% toluene solution of Paraloid B-72 onto the surface.  The varnish on the lid was removed with ethanol and a new bleached shellac finish was applied. After the B-72 and the newly finished lid was cured, the entire surface was paste waxed with Liberon #0000 steel wool.

After B-72 was applied

The detached molding was readhered with animal hide glue. The small missing portion was repaired with a carvable epoxy putty. Once the putty was cured in place, the molding profile was carved with chisels. The epoxy fill was then inpainted with NGR dyes, shellac, and earth pigments.

Epoxy fill carved

Dye penetrates the fill

Shellac and pigments add patination

Final molding graft with mottled finish and worn surface to match patina.


The later desk top finish was removed for reapplication of leather on the writing surface. This was removed with a combination of ethanol and mild mechanical scraping. Once the substrate was prepped it was coated with hot animal hide glue and the leather was applied to the surface. After the hide glue was dry, the perimeter was cut with a razor blade.

After Treatment

After Treatment

After Treatment

After Treatment

After Treatment

6 comments:

  1. Really great work,an expert!!

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  2. Where do you get "gelled ethanol"? Is this something you make or something you buy?

    ReplyDelete
    Replies
    1. Any solvent can be gelled by adding a thixotropic agent such as Carbopol or Pemlulen but this case is simply hand sanitizer. This is the only commercially available gelled solvent I am aware of so any other solvent would need to be mixed up yourself. Thanks for your interest!

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  3. Thanks! I learned something new.

    Thixotropic--pretty cool.

    Is there an advantage to use a gel over just placing an ethanol-soaked rag on top of the area? Slower evaporation? But that would affect the vapor pressure on both sides of the rag (artifact below and air above). ???

    ReplyDelete
    Replies
    1. Yes, it slows evaporation. But also it prevents the solvent from soaking the barrier towels. You DO NOT want the towels wet with solvent or the finish surface will be marred. The vapor is doing the work not direct application of solvent.

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  4. Your work and knowledge brings me great pleasure. I enjoy your study and approach to your subject.

    ReplyDelete